Electric position indicator



ELECTRIC POSITION INDICATOR Filed July 4, 1942 wnutsszs: INVENTOR firresl S Mabqy. 4 BY ATTORN EY Patented Feb. 20, 1945 ELECTRIC POSITION INDICATOR Forrest S. Mabry, Catonsville, Md., assignor to Westinghouse Electric & Manufacturing Gompany, East Pittsbur Pennsylvania gh, Pa., a corporation of Application {my 4, 1942, Serial no. 449,70;

12 Claims.-

My invention relates to electric position indicators and, more particularly, to electric means for accurately tuning radio equipment.

In many radio transmitter tuning dials, as mg as fifty revolutions on the control dial are required to tune from one end of the tuning band to the other end of the tuning band. In actual use, there are really only a few definite points in the entire tuning band that are normallyused, and it is very helpful if these relatively few points can be quickly and accurately indexed. Mechanical clicker devices for such tuning are known in the prior art, but these devicesarenot sufiiciently accurate.

One broad object of my invention is to electrically indicate with accuracy the location of a machine element.

A more specific-object of my inventionisthe provision of means for electrically indicating with accuracy when radio equipmentin the tuning operation thereof, has been tuned to a selected wave length.

The foregoing recited objects are merely illustrative, and many other objects of my invention will, no doubt, become apparent from a study of the following, specification and the accompanying drawing, in which:

Figure 1 is a. side view of one embodiment of my invention;

Fig. 2 is a perspective view of a modification of my invention; and I Fig.3 is an enlargeddetail of a portion of the subject-matter of my invention shown in Fig. 2.

To facilitate the disclosure of my invention,

I have shown the elements somewhat .diagram- .1.

matic.

In Fig. 1, l designates; the tuning equipment for a radio transmitter, or for that matter any other type of tuning equipment, or other machine, having elements the exact'location of which during operation is to be determined.

To operate the. tuning equipment, I show a handwheel 2 for operating theshaft 3 which, in turn, operates the; mechanisms of ,the tuning equipment. The handwheel has the actuating handle 4 and is usually provided with graduations onits face, or edge,-or both, for coacting .With the index -5. T,o save time, the handwheel is rapidly operated to about the desired, tuning p sition and-then the Vernier mechanism 6 may be'actuated to slowly and accurately operate the tuningequipment.

The Vernierequipment may, of course, take any desirable form, but as shown, includes -a spring biased shaft having an operating knob-1 and a pinion 8 for engaging the gearteeth 9 onthe handwheel-2. By slowly-moving the knob, a very slow tuning operation may be effected.

Toiaccurately indicate when a certain tuning operation is effected, I provide a plurality of adjustably mounted position indicators generally indicated by N, H and I2, respectively. These units are allalikeand a description of one will thus suflice.

The base. I3 is slidably mounted in the subbase 14, and when the apparatus is set up, the

base: is ,movedto'the exact desired position and then clamped, in position on the sub-base by the heads of screws Hand 1 6.

On the base, I'pivotally mount a lever l 1. This lever is normally biased by spring 20 to the position shown at the right in Fig. 1, in which position contacts [8 and I9 will be in engagement. When the lever has been actuated, the lever will trip counter-clockwise to a position as shown for levers 2| and 22.' The lever then makes contact with stop 23, and the biasing force of spring 20 now is to the left of pivot 24; The lever thus remains in the counter-clockwise position.

The position indicating circuit includes a battery B, a light L, a slip-ring assembly S, the shaft 3, which is'threaded as shown to receive the conductive traveling nut 25, contact 26 on nut 25, contact flon lever, l1, lever l1, contact lBon lever I'l, adjustable contact l9, back to the batter-y.

Aibetter' understanding can, no doubt, be had "from a study of atypical operation. Suppose an accurate tuning is to be effected for the position to beindicated by lever 11. The attendant operates, handwheel 2 through knob 4 until nut 25 is in the neighborhood of lever H, but preferably still tothe left of this lever. Then through suitable actuation of the verniermechanism, the nut 25 is slowly moved toward the right. As soon as the correct positionv is attained, contacts 26 and 21 close thus establishing the circuit hereinbefore traced; A very accurate indication of the correct. point is thus indicated by signal light L, .because the rigid pivoted lever l1 permits the closure of contacts."l8.and l9 and 26 and 21 only over an extremely short excursion of nut 25. For example, if .nut 25 is .still to the left .of the correct position by as little as 0.001 of an inch, the circuit -.for--signal-light- L would be open at contacts 26 and 21, and if the nut 25 is moved to the right of the correct position by as little as 0.001 of an inch, the circuit for :thesignal light L would be opened-at contacts 18 and I9. Thus, the accuracy; of the indication, depending of course on the accuracy of making the various parts, would be of the order of +0.001 inch.

This degree of accuracy may be excessive in some cases so that it may be desirable to make the contacts l8 and 21 more or less resilient, as shown. This will give a greater tolerance to the position of nut 25 during which the signal light would be energized, and thus a greater tolerance in the tuning whenever such tuning tolerance is permissible.

I have shown a plurality of indicating positions as is evidenced by levers 2| and 22. As nut 25 is moved to the right, all those levers to the left of nut 25 will be tripped, as shown. On return movement of the nut 25, the nut engages the arms 30, 3| 32, etc., to set all the levers.

To make the device operative in either direc tion, the levers 2|, 22, etc., may be modified as shown in Fig. 3. The levers need not necessarily be actuated by a traveling nut, but may be actuated by a suitable disc, as disc 40 shown in Fig. 2, having one or more projections, as projection 4|.

In the showing in Fig. 2, the levers are all mounted for individual circumferential adjustment about disc 49 on individual bases (not shown to clarify the disclosure) corresponding to the bases |3 I3 and I3" shown in Fig. 1.

To eiiect accurate tuning, the handwheel 42 is first actuated directly by knob 43 until projection 4| is somewhere near the desired position, which position can be read ofi the graduationson the handwheel in relation to the fixed index shown. The Vernier mechanism 44 may then be clutched to handwheel 42 and manipulated to slowly move the disc 40 to the correct position.

At the instant the desired tuning is effected, a circuit is established from battery B, the slipring assembly 45, the disc 40, projection 4|, contact 46 which may be slightly resilient, lever 41, contact 48 which may also be slightly resilient, adjustable contact 49, signal light 50 to the battery B. Again, if the projection, or contact, 4| is just short of the desired position, contacts 4| and 46 are open, and when a trifle too far in the clockwise position, contacts 48 and 49 are open.

To make the indication equally effective for either direction of rotation, it is clear that contacts 46, 48 and 49' should be so positioned that the contacts 48' and 49' and contacts 4|-and 46 are closed, on counterclockwise rotation, when projection 4| is in exactly the same mechanical position as it was when contacts 4| and 46 and 48 and 49 were closed. That this can readily be done can be seen from Fig. 3. When the projection is in clockwise position beyond the position shown, the lever 41 will take a position such as is shown for lever M1 in Fig. 2. Then upon rotation of disc 40 in the counter-clockwise direction, contacts 4| and 46 and 4B and 49' will close when contact 4| is in exactly the same position it held when contacts 4| and 46 and 48 and 49 were closed. H

In the modification shown in Fig. 2, each tuning position may be provided with its own signal light. The lights may have different colors, have different illuminated numbers or other indicating indicia adjacent the lights.

In both modifications, it is, of course, clear that the needed electric insulation is provided in the locations desired so that no stray electric circuits are provided.

From the foregoing, it will be seen that I have provided an electric system for accurately indicating the position of a machine element, but I do not wish to be limited to the specific showing made but wish to be limited only by the scope of the claims hereto appended.

I claim as my invention:

1. In an electric system, in combination a source of electric energy, an electric device having a characteristic indicating when the device is energized, and an electric circuit for connecting the electric device to the source of energy, said circuit including a stationary contact, a rotatable member, an overcenter-type spring for biasing the rotatable member when said member is in one position for clockwise rotation and when said member is in another position for counter-clockwise rotation, a first switch contact on the rotatable member facing said stationary contact and making contact with the stationary contact when the member is biased for clockwise rotation, a movable contact for rotating said rotatable member in a counter-clockwise direction to interrupt the connection between the first switch contact and the stationary contact, a second switch contact on'the rotatable member, electrically connected to the first switch'contact, said second switch contact being disposed in the path of the movable contact, whereby a circuit is established for the electric device through the movable contact, the two switch contacts on the rotatable member and the stationary Contact only when the movable contact has just made contact with the second switch contact on the rotatable member but has not yet rotated the rotatable member sufiiciently to interrupt the connection between the stationary contact and the said first switch contact.

2. In an electric system, in combination, a source of electric energy, an electric device having a characteristic indicating when the device is energized, and an electric circuit for connecting the electric device to the source of energy, said circuit including a stationary contact, a rotatable member, an overcenter-type spring for biasing the rotatable member when said member is in one position for clockwise rotation and when said member is in another position for counter-clockwise rotation, a first switch contact on the rotatable member facing the stationary contact and making contact with the stationary contact when the member is biased for clockwise rotation, a movable contact for rotating said rotatable member in a counter-clockwise direction to interrupt the connection between the first switch contact and the stationary contact, a second switch con tact on the rotatable member, electrically connected to the first switch contact, said second switch contact being. disposed in the path of the movable contact, whereby a circuit is established for the electric device through'the movable contact, the two switch contacts on the rotatable member and the stationary contact only when the movable contact is moved through an extremely small range of its total range of movement, and means on the rotatable member for resetting the position thereof by the mpvablecontact, if it is in the overcenter counter-clockwise position, by a return movement of the movable contact.

3. In an electric circuit system, the sub-combination of, a bifurcated electrically conductive lever pivoted near the base of the bifurcation, two stationary contact members, one disposed at each side of the nonbifurcated end of the bifurcated lever, a spring of the'overcenter-type for biasing the lever so that the nonbifurcated end contacts either one or the other of said stationary contact members depending on the position of the lever, a movable contact member when in a given posilever so that the nonbifurcatedend contacts the stationary contact member or is biased away-from the stationary contact member depending: on the position 01 the lever, amovable-contact member when in agiven position adapted to .engage the inner side :of the end of onebifurcation when the leverisin one position and adapted toengage the inner side of the endof the,- other-bifurcation when the lever isrinits other position;

5; In an electric system for indicating the-position of a machine; element, in combination, a source. of electric: energy, an electric-signal; device,

a pair of-switcheswhichwhenzboth are closed establish acircuit fromthe source of ener y, through thetwo ,switches, through, the electric signal devicepback to, the source ofelectric energy, said switches includin -abirurcatedlever, a-stationary contact: memberpdisposed: at" onecsi'de of the DODblflXICfltGdgBIXdj of thelever, a spring. of the overcenter-typa for biasing the lever so, that the nonbiturcatedend contacts the stationary contact member or is biased away; from-the stationary contact member depending-on the pOSition of the lever, amoyable machine element, the position of which is to be indicated, a contact, mounted on the movable machine element, adapted to engage the inner side of the one end of the bifurcation as the machine in its movement arrives at a given position and adapted to trip the lever to open the circuit between the lever and the stationary contact member as the machine element moves beyond the said given position, said contact on the machine element being adapted to engage the inner side of the end of the other bifurcation when the lever is in its tripped position and the machine element is moving in a reverse direction.

v6. In an electric system for indicating the position of a machine element, in combination, a source of electric energy an electric signal device, a pair of switches which when both are closed establish a circuit from the source of energy, through the two switches, through the I electric signal device back to the source of elecreturn-movement again arrived atthe said given.

, position and to trip the-:lever-to its original positrio ener y, said switch including a bifurcated cated end of the bifurcated lever, a spring of the overcenter-type for biasing the lever so that the nonbifurcated end contacts either one or the other of said stationary contacts depending on the position of the lever, a movable machine element. a contact on the machine element adapted toengage, as the machine element moves in one ,direction, the inner side of the end of one bifurcation to establish a circuit for the signal device when the machine element has arrived at a given position and to trip the lever to its other position if the movement of the machine element is continued beyond the given position, whereby only a very transient circuit is established for the signal device, said contact'on the machine sale tion if 1 the return movement of the machine element iscontinued :to 1a =point ahead 'of said given position, wherebyagain only a verytransient circuit is established for'the signal device;

7 In-a systemof control fOrrtUIliIlg radio equipment; in combination, a tum'ngmechanism, a machinev element :movable. asa function of :the tuning mechanism said radio equipment havin a pluralityof tuning. positionsaaplurality of means for indicating. the tuning; positions;v said means includingamsourceaof energy; a signal device, and, for. each, tuning;- positiom, a stationary contact, movably mounted switching, means biasedto make contact with, the, stationary contact, a second movable; switching means operable to move-the first movableswitching meansto break the con tact with the stationary contact, but which second movable switching means. atthe instant when it first makes contact with the-first movableswitching mean-s closinga; transient-circuit to indicate the particular tuning-positionwto beindicated. the circuit being transient onlyif the movement of the secondmovabletswitchingmeans When first contacting thersecond; movable switchingmeans is reater inthe. directionofits movement than a relatively small fraction of its entire range of movement.

8., Inan electric system, in-combinat oma subbase, a, base, means forfixingthe base in any one of a plurality of adjusted positions on the subbase, electric means for indicating the position of adjustment of the base with reference to the subbase, a contact fixed on the base, a pivoted conducting bar on the base, said bar having a given range of angular movement and be ng biased so that one side near one end engages the contact, a movable contact on the sub-base, said movable contact having a path of movement on the subbase so that it can make contact with the opposite side and opposite end of the conducting bar, regardless of the position of adjustment of the base with reference to the sub-base, to rotate the bar against its bias to thus, the instant the bar is engaged, interconnect the source of supply and the means for indicating the position of adjustment of said base on the sub-base and to break .this interconnection by any rotation of the bar in excess of a small angular rotation with reference to the total range of angular movement of said bar.

9. In an electric system, in combination, a source of energy having two terminals, an electric device, a, circuit for connecting said device to said source of energy, said circuit including a stationary contact connected to one terminal of said source of energy, a movable conducting bar, having a given range of movement, biased to engage the stationary contact at one point, and a movable contact, connected to the other terminal of said source, movable in a direction to engage the conducting bar at another point and to move the conducting bar to immediately break the contact between the stationary contact and the conducting bar upon a small movement of the conducting bar with reference to its total range of movement.

10. In an electric system, in combination, a sub-base, a base, means for fixing the base in any one of a plurality of adjusted positions on the sub-base, electric means for indicating the position of adjustment of the base with reference to the sub-base, a resilient contact fixed on the base, a pivoted conducting bar on the base, said bar having a given range of angular movement and being biased so that one side near one end engages the contact, a resilient movable contact on the sub-base, said movable contact having a path of movement on the sub-base so that it can make contact with the opposite side and opposite end of the conducting bar, regardless of the position of adjustment of the base with reference to the sub-base, to rotate the bar against its bias to thus, the instant the bar is engaged, interconnect the source of supply and the means for indicating the position of adjustment of said base on the sub-base and to break this interconnection by any rotation of the bar in excess of a small angular rotation as determined by the resilient character of the contacts with reference to the total range of angular movement of said bar.

11. In an electric system, in combination, a source of electricenergy, an electric signal device,

and a circuit for connecting the electric signal device to the source of electric energy, said circuit including a stationary contact, a substantially rigid conducting bar pivoted intermediate its ends and biased for rotation about its pivot in one direction so that said bar makes contact with one side of one of its ends with the stationary contact, and a movable contact disposed to move into engagement with the other side of the other end of the bar, and means for moving the movable contact to rotate the pivoted bar counter to its bias, whereby a circuit is established for the signal device only when the movable contact is moved sufiiciently to engage with the said other side of the other end of the bar but not suificiently to rotate the bar to break the contact it makes with the stationary contact.

12. In a system of control for the tuning of radio equipment, in combination, a tuning mechanism; a machine element movable in proportion to the tuning mechanism; said radio equipment having a plurality of means indicating tuning positions, said means including a source of energy, a signal device, and, for each tuning position, a stationary contact and a switch member pivoted intermediate its ends, said switch member having a contact on one side at one end, said switch member being biased about its pivot point so that the contact it has on one side at one end engages the stationary contact, said switch member having a second contact on the other side at the other end disposed in the path of said machine element; and a contact on the machine element disposed to successively contact the second contact on each of the switch members to establish, at each tuning position, an energizing circuit for the signal device when the machine element in its movement in a given direction has arrived at a given tuning position but operable, upon causing the slightest rotation of the switch member counter to its bias by continued movement of the machine element in the given direction, to open the circuit for the signal device, and, upon the slightest movement of the machine element from a given tuning position in a direction opposite to the given movement, to open the circuit for the signal device.

FORREST S. MABRY. 

